1. Field of the Invention
The present invention relates to an electric connection box to be mounted on an automotive vehicle or the like and, more specifically, to an electric connection box in which joint connectors for connecting external electrical wires are formed so as to open toward the outside of a case.
2. Description of the Related Art
In the related art, an electric connection box is used in an automotive vehicle or the like for the purpose of improvement of both efficiency of electric wiring and maintenanceability. JP-A-2007-181317 is an example of the related art. An internal circuit is formed in the interior of the electric connection box, and detachable connectors are employed for connecting external electrical wires to the internal circuit.
The connector generally includes a plurality of substrate terminals formed on a circuit substrate, which constitutes the internal circuit, so as to project therefrom. The plurality of substrate terminals project to the outside through insertion holes provided on a case of the electric connection box. The case is formed with connector peripheral wall portions which surround the peripheries of the plurality of substrate terminals.
However, the connectors having the structure as in the related art have a risk of occurrence of connection failure of the terminals when connecting the connectors. In other words, since the substrate terminals are provided on the circuit substrate, which is a separate member from the case having the connector peripheral wall portions to be fitted to external connectors, the projecting height of the substrate terminals tends to be small if the circuit substrate is deflected by a pressing force or the like applied when joining the connectors.
Therefore, there is a risk of occurrence of the connection failure such as resistance increase because of insufficient contact surface areas between the substrate terminals and external connecting terminals even when the external connectors are reliably fitted and connected to the connector peripheral wall portions.
In particular, when the substrate terminals are configured by fixedly press-fitting press-contact terminals to an insulating plate having electric wires such as covered single conductor cables laid thereon (hereinafter, referred to as a wired insulating plate), the press-contact portions of the press-contact terminals to the electric wires project with respect to the back surface of the wired insulating plate. Therefore, it is difficult to reinforce and support the portions of the wired insulating plate formed with the external connectors by a case or the like from the back surface, and hence the terminal-to-terminal connection failure due to the deflection of the substrate (wired insulating plate) might become a serious problem.
When the external connector has an elongated shape and a plurality of such elongated external connectors are arranged in parallel, spans (free lengths) of areas of the wired insulating plate, whose back surfaces are neither reinforced nor supported by the case or the like, are subjected to further deflection. Therefore, the deflection of the substrate of such portions is further increased, so that the above-described terminal-to-terminal connection failure might become a further serious problem.
Improvement of rigidity of the wired insulating plate by increasing the thickness is also conceivable. However, it results in an increase in size and weight of the entire electric connection box and an increase in cost due to an increase of required material. Therefore, it is hardly a sufficient countermeasure.